I will stick with the N900 for the foreseeable future.

The only phone I can really accept is an upgraded N900, with an update Maemo (well, some other, similar OS would be fine, but there is nothing practical on the horizon)

The N950 comes close, but it has the wrong kind of touch screen. Those things are too weird and sensitive, and need a special stylus (and I don't think it comes with one, or a slot for one). Hartman might be ok (still Maemo underneath, not "true" Meego), although really I am rather fond of Hildon.

But even things like Mer are off in rpm/qt land now, so I think the only way to get newer Maemo would be to become a good enough programmer, and do it myself. And no one with the necessary resources cares about the needed hardware.